MantraProcedurals

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What is a MantraProcedural?

A procedural is a plugin to that will allow mantra to generate geometry on the fly at render-time.

Implemented procedurals

Mantra has the following procedurals in the standard distribution:

HScriptInstanceProcedural : tell mantra of a node type and its parameters and it will generate the geometry for you at render time.
- Caveat: This will call hscript (and use an hscript license) for each object rendered this way.
SpriteProcedural : mantra will instance cards (quads) onto supplied particle points and apply a shader to it.
FurProcedural : mantra will procedurally generate fur/hair based on a skin mesh as well as optional guide, clump and parting curves.
Image3DIsoTextureProcedural : an IsoSurface will be generated from an i3d file.
PolygonizedMetaballsProcedural : mantra will generate a polygonal mesh from supplied Metaballs. Note: This method is not as efficient as rendering metaballs directly in mantra.
- This allows for displacement shading of metaballs
- This allows for motion blur of metaballs
RunExternalProgramProcedural : mantra can execute an external program to generate geometry for the beginning and end of frame (for MotionBlur purposes)

Making your own procedurals

Where to look

You'll want to look at the VRAY_Procedural.h header file.
If your procedural is based on an iso-surface, you might also want to look at VRAY_ProcIsoBase.h which has a method called evaluateDensity() (similar to the GU_Iso.h class)
In the samples, there's a very simple VRAY_DemoBox procedural which renders a box as it's procedural.

Installing a new procedural

Aside from the built-in procedurals, you have to tell mantra where your plug-in procedural can be found. This is done by installing a file called VRAYprocedural (please see the VRAY_DemoBox for an example of this).

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